1. Field of the Invention
The invention relates to an image reading apparatus and, more particularly, to an image reading apparatus such as an image scanner or the like for inputting an image to, for example, a personal computer and other information processing apparatus.
2. Related Background Art
Information equipment having an advanced function and multifunctions represented by a personal computer is widely spread, and by connecting various peripheral equipment thereto, the information equipment can be allowed to perform a variety of works. As such peripheral equipment, there are image input apparatuses such as image scanner, electronic still camera, digital video camera, and the like. Particularly, the image scanner is widely used as means for converting documentation information to electronic data or for recording it as an image.
FIG. 6 shows a schematic constructional block diagram in which an image scanner is connected to a personal computer.
In an image scanner 110, reference numeral 112 denotes a CPU for controlling the whole scanner 110; 114 an image reading unit which is constructed by a light source, a CCD line sensor, and the like and converts an image of an original to an electric signal; 116 an analog signal processing circuit for performing an analog process such as a gain control or the like to an analog image signal which is outputted from the image reading unit 114; 118 an A/D converter for converting an output of the analog signal processing circuit 116 to a digital signal; 120 a digital image processing circuit for performing image processes such as shading correcting process, gamma converting process, variable magnification process, and the like to output data of the A/D converter 118 by using a memory 122; and 124 an interface for outputting the digital image data which was image processed by the digital image processing circuit 120 to the outside. The interface 124 is based on the standard such as, SCSI, Bi-Centronics, or the like which is used as a standard interface in a personal computer. The interface 124 is connected to a personal computer 130.
As an external storage device 132, a magnetooptic disk drive, a floppy disk drive, or the like is equipped to the personal computer (hereinafter, abbreviated as a PC) 130.
FIG. 7 is a flowchart showing the operation of the image scanner shown in FIG. 6. When a start command to start the image reading operation is issued from the PC 130 to the image scanner 110, the interface 124 analyzes the command from the PC 130 and notifies the CPU 112 of an analysis result. Prior to performing the process corresponding to the notification, the interface 124 outputs an interruption signal indicating that there is the instruction to start the image reading operation from the PC 130 to the CPU 112. When the interruption signal of the reading start instruction is received from the interface 124, the CPU 112 instructs the start of the reading operation to the image reading unit 114, analog signal processing circuit 116, A/D converter 118, and digital image processing circuit 120 (step S101).
First, the image reading unit 114 sequentially reads the image of the original (S102). The analog signal processing circuit 116 executes processes such as a gain control and the like to the analog image signal that is outputted from the image reading unit 114 (S103). The image signal processed by the analog signal processing circuit 116 is converted into a digital signal by the A/D converter 118 (S104). The digital signal is temporarily stored in the memory 122 and is subjected to a digital image process by the digital image processing circuit 120 (S105). As image processes which are executed by the digital image processing circuit 120, there are a shading correcting process for correcting variations of a light source and a line sensor or the like by image data serving as a white reference, a gamma converting process for changing gamma characteristics of the input image data, a variable magnification process for reducing or enlarging an image in accordance with an image size to be outputted, and the like. Any one of those processes is executed by using the memory 122 connected to the digital image processing circuit 120.
The image data processed by the digital image processing circuit 120 is sequentially transferred to the interface 124 (S106). The reading operation and the transferring operation of the image in steps S102 to S106 are repetitively executed until the reading operation of the whole area or all of the designated range of the original is finished (S107).
The interface 124 converts the image data transferred from the digital image processing circuit 120 to image data of a format according to the transfer standard with the PC 130 and sequentially transfers the converted image data to the PC 130. The PC 130 displays the image data sent from the image scanner 110 (specifically speaking, interface 124) onto a screen of a monitor display of the PC 130. The PC 130 stores the image data from the image scanner 110 to an internal hard disk (not shown) as necessary. To preserve the read image data for a long time or to use it by another computer, the image data stored in the hard disk is read out and copied to a storage medium such as magnetooptic disk, floppy disk, or the like by the external storage device 132.
In such an image scanner, while the original is being read, the read image data is sequentially transferred to the PC 130. Therefore, so long as the PC 130 cannot simultaneously make a plurality of application softwares operative, another application software cannot be used until the end of the reading operation of the original.
In case of reading the original in color, since its data amount is extremely large, it takes a longer time to transfer the image data from the image scanner 110 to the PC 130 by a time corresponding to such a large data amount and a time that is occupied in the PC 130 is long. In case of a color image, further, when considering a copy to an external storage medium such as magnetooptic disk, floppy disk, or the like, an enough space capacity of the internal hard disk also needs to be assured.
Further, the personal computer is connected to a network and used and an image input apparatus such as an image scanner or the like serving as peripheral equipment of the computer can be also connected to the network. However, in case of the image scanner, there are the following problems. That is, in case of reading an original by the image scanner, the original is put on an original base plate and is first prescanned at a low resolution. A read image is confirmed on a monitor screen, a range to be actually read, a reading resolution, or the like is designated, and the image scan is executed. In case of connecting the image scanner to the network and using it, the operator has to reciprocate at least twice between the own computer and the image scanner in a manner such that                (1) he goes to the image scanner and puts the original thereon,        (2) he returns to his seat and designates a scanning range and a reading resolution while looking at a preview image by a monitor screen of a client computer, thereby allowing the scan to be executed, and        (3) he goes to the image scanner and gets the original.        
When the original is obliquely put on the original base plate, he has to further reciprocate between the own computer and the image scanner in order to correct the position of the original. Since a period of time when there is no original on the operator side is long, there is a possibility such that the original is lost due to a theft or the like.